JPH0346691A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce the cost of a liquid crystal display device and to improve the yield thereof by dividing a printed wiring board having circuit wiring which is inputted to respective tape carriers and forming small-sized printed wiring boards. CONSTITUTION:By dividing the printed wiring board 14 having the circuit wiring which is inputted to the respective tape carriers 13X and 13Y and forming the small-sized printed wiring boards 14a - 14d, the terminals of the printed wiring boards 14a - 14d can be soldered and connected to the tape carriers 13X and 13Y before they are integrated on the rear side of liquid crystal panels 11A and 11B. Since the soldered connection can be executed at the position which is separated from the polarizing plates of the liquid crystal panels 11A and 11B, the polarizing plates are not contaminated by flux, a solder or the like. Besides, since the printed wiring boards 14a - 14d are interposed by a set of supporting bodies 21 and 22, they are easily and surely arranged to a prescribed position and the assemble condition thereof is excellent. Thus, the cost of the liquid crystal display device is reduced and the yield thereof is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a liquid crystal display device with an improved mounting structure for driving ICs and the like.

(Prior Art) In various liquid crystal display devices such as liquid crystal televisions, the display portion is formed to be large, but electronic circuits other than the display portion are desired to be assembled as small and compact as possible.

By the way, conventionally, wire bonding (hereinafter referred to as WB), tape automatic bonding (hereinafter referred to as TAB), flip chip bonding (hereinafter referred to as PCB), etc. are used to assemble this type of electronic circuit. All of these use bare ICs as drive ICs, and are designed to be more compact than those packaged in flat packages.
C. This can be called a high-density packaging technology.

Among these, TAB is better in mass production than WB, has better stress reliability than PCB, and can easily be mixed with passive component chips such as resistors, capacitors, and inductors for spurious noise reduction filters. For this reason,
It is widely used as an IC mounting technology for various liquid crystal display devices such as liquid crystal televisions.

For example, in a high-definition, high-quality LCD TV, the diagonal of the display area of the glass substrate of the LCD panel is 4 inches, and approximately 100,000 thin film transistors (hereinafter referred to as TPTs) are installed in the display area.
are arranged with regularity in the row and column directions. Each of these TPTs constitutes a unit pixel, and is connected to an independent transparent electrode for each unit pixel area, and by applying a certain potential to a counter electrode provided through the liquid crystal, the liquid crystal Open the shutter.

Each of the above TPTs is connected to a large number of terminals arranged around the peripheral edge of the glass substrate by parallel lead wires in both the row and column directions. For example, a 4-inch diagonal device has 220 terminals in the row direction and 480 terminals in the column direction, and by applying voltage to these terminals at a controlled predetermined timing, the corresponding TPT can be set. The liquid crystal shutter corresponding to this TPT opens and closes (including halftones). Therefore, by overlaying color filters on these liquid crystal shutters to allow light to pass through, full color display becomes possible.

As mentioned above, 220 terminals in the row direction and 480 terminals in the column direction are provided on the peripheral edge of the glass substrate of the liquid crystal panel, and the connection structure between these terminals and the driving IC becomes a problem. For example, in the column direction, the opposite sides are also used, so if 240 lines are connected to the - side of 80 mm,
The pitch of the terminals is 333 μm. Furthermore, assuming that 220 terminals are connected on a side of 60+ nm in the row direction, the pitch of the terminals is 272 μm, which requires a technique for connecting a large number of high-density terminals.

Conventionally, as shown in FIGS. 5 to 7, a plurality of tape carriers 13 are provided with a large number of terminals provided on the periphery of a transmissive liquid crystal panel 11 and a plurality of tape carriers 13 on which bare driving IC+2 are mounted.
The tape carrier 13 is bent into a U-shape on the back side of the liquid crystal panel 11, and the terminal on the other end of the tape carrier 13 is connected to the drive IC+2.
It is connected to a terminal of a printed wiring board 14 based on a glass epoxy laminate on which circuit wiring is formed. This printed wiring board 14 is connected to the liquid crystal panel 1.
It has an opening 15 facing the display section 1, is equipped with a control IC 16, and is connected to a signal input/output cable or signal output body 17 such as an FPC.

When connecting the driving IC 12 and the tape carrier 13, a gold (Au) bump is formed on the terminal of the driving ICI 2, and a tin (Sn) plating is formed on the copper (Cu) lead of the tape carrier 13. Apply.

After aligning these connection positions, heat and pressure are applied to form Au/Sn eutectic and bond them together. There are 120 output terminals of the driving ICI 2, and 120 output terminals of the tape carrier 13 connected thereto are made in accordance with the pitch and number of the terminal group of the liquid crystal panel 11, for example, at a pitch of 333 μm. After these are opposed to each other, an anisotropic conductive film is interposed between them, and they are connected by heating and pressurizing them. As mentioned above, the number of terminals per side in the column direction is 240, and the number of terminals on the tape carrier 13 is 120, so the number of terminals per side is 240.
Two tape carriers 13 are used. In addition, the anisotropic conductive film is, as is well known, a strip-shaped thin film made of an organic material dotted with conductive particles, and the resin is softened and crushed by heat and pressure, and the conductive particles respond. The terminals of the liquid crystal panel 11 and the tape carrier 13 are sandwiched between the terminals.

(Problem to be solved by the invention) The conventional device described above has the following problems.

First, since the printed wiring board 14 having the circuit wiring input to each tape carrier 13 uses a transmissive liquid crystal panel 11, as shown in FIG. It has a large shape with an opening 15 at the top. As a result, when the size of the display portion of the liquid crystal panel 11 increases, the cost of the printed wiring board 14 increases, which in turn increases the cost of the entire liquid crystal display device.

Second, in order to reduce the size of the liquid crystal display device, it is desirable that the width of the frame portion formed on the outer periphery other than the display portion be as small as possible. Therefore, as shown in FIG. Although the gap l between the display section and the printed wiring board 14 is designed to be small, during assembly work, the flux, solder, etc. used for soldering the printed wiring board 14 and the tape carrier 13 may be applied to the outer surface of the liquid crystal panel 11. The particles scatter onto the polarizing plate 18, contaminating it and making it a defective product.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that solves the above-mentioned problems, reduces costs, and has a high yield during assembly.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a transmissive liquid crystal panel and a plurality of tape carriers each equipped with a driving IC that is connected at one end to a terminal on the periphery of the liquid crystal panel and drives the liquid crystal panel. and a printed wiring board connected to the other end of each tape carrier and having circuit wiring input to each tape carrier, wherein the printed wiring board has at least two
The tape carrier on at least one side of the liquid crystal panel is bent at the outside of the connection part with the liquid crystal panel, and the printed wiring board connected to the tape carrier is placed on the back side of the liquid crystal panel. The printed wiring board is held between a pair of supports disposed on the back side of the liquid crystal panel.

(Function) In the present invention, by dividing and forming a printed wiring board having circuit wiring input to each tape carrier into small printed wiring boards, the printed wiring board is connected to the tape carrier before being glued to the back side of the liquid crystal panel. Connection can be made by soldering to the terminals of the printed wiring board, and since this soldering can be done at a position away from the polarizing plate of the liquid crystal panel, the polarizing plate will not be contaminated with flux, solder, etc.

Moreover, the printed wiring board can be easily and reliably placed in a predetermined position by being held between the pair of supports, and has good assembly efficiency.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Note that parts corresponding to the configurations in FIGS. 5 to 7 will be described with the same reference numerals.

In FIGS. 1 to 4, the liquid crystal panel 11 includes two glass substrates 11A and IIB, which are provided with a large number of TPTs, transparent electrodes, etc. constituting unit pixels, as in the conventional case. .

A liquid crystal is sealed between IIB. Further, the glass substrate 11A on the back side is larger than the glass substrate 11B on the front side, and its edges protrude outward. In addition, as the liquid crystal panel 11, the so-called TPT using the above-mentioned TPT is used.
It does not need to be a PT-LCD, and may be any other active matrix display device or dot matrix display device. In any case, the liquid crystal panel 11 has glass substrates 11A and IIB, and the glass substrate +
A large number of terminals for driving pixels are arranged on the peripheral portion of 1A (three sides in the illustrated case). Regarding the number of terminals, that is, the number of terminals in the vertical direction and the number of terminals in the horizontal direction, for example, a liquid crystal panel with a diagonal of 4 inches requires 220 terminals in the vertical direction and 480 terminals in the horizontal direction.

As a driving IC that drives each pixel via each of these terminals, for example, 110 elements are used in one for the vertical direction.
A device built in the chip is used, and in the horizontal direction, a device with 120 elements built into one chip is used. That is,
The vertical direction is driven using two 1-10 element ICs, and the horizontal direction is driven using 4 1-20 element ICs.

Here, the vertical and horizontal sides of the 4-inch diagonal display are 60 m.
m x 80 mm. If the pitch of the terminals arranged on the periphery of the liquid crystal panel 11 is smaller than 200 μm, the connection technology will be sophisticated and the connection will be difficult. The terminal pitch is 333 μm.

Also, the terminal pitch is 272μm even if there is only one vertical side.
Therefore, two ICs are placed on one side.

IC12Y for vertical direction and I for horizontal direction as above
C12X are mounted on and electrically connected to a plurality of corresponding table carriers 13Y and 13X, respectively. As in the past, this connection is made using I Cl2X, 12Y terminals with gold (Au) bumps formed thereon, and a polyimide film-based tape carrier 13x with copper (Cu) leads plated with tin (Su).

After aligning the position with the terminal of 13Y, Au/Sn eutectic formation is performed by heating and pressurizing and bonding is performed. Hereinafter, this will be referred to as I L B (Inner Lead Bonding).
It is called.

Next, drive IC+2X as described above.

Tape carriers 13X and 13Y loaded with +2Y are connected to terminals on the periphery of the liquid crystal panel 11. Hereinafter, this will be referred to as OL B (Oute "Lead Bonding")
It is called. This connection is made using an anisotropic conductive film. That is, the terminal of the liquid crystal panel 11 and the tape carrier 13X
, 13Y are formed at the same pitch as the output terminals on the one end side, and after aligning these positions, an anisotropic conductive film is interposed and heat and pressure are applied to connect them.

The printed wiring board 14 is divided into four elongated printed wiring boards 14 corresponding to each side of the liquid crystal panel 11.
a, 14b, 14c, 14d, of which three printed wiring boards 14a, 14b,
The terminal groups of the driving I Cl2X and 12Y are individually connected to the driving I Cl2
Circuit wiring is formed to apply specific voltages and signals to the X and +2Y input terminals. In addition, the other printed wiring board +4d is provided with a control IC+6, and a signal input/output cable or FPC
The IC 1 is connected to the signal output device 17, and is used for driving the printed wiring boards 14a, 14b, 14c.
2X.

Control IC16 to control the drive to 12Y
Circuit wiring is formed to provide control signals from. And the tape carrier +3X of the liquid crystal panel 11,
Printed wiring boards 14g, 14b, and 14c divided for each side having 13Y are arranged, respectively.
The input terminals at the other ends of the tape carriers 13X, 13Y are connected to the terminals of the printed wiring boards 14a, 14b, 14c by soldering, respectively.

Reference numerals 21 and 22 are a pair of plate-shaped supports made of synthetic resin such as ABS resin. The first one above this
The support 21 is provided with an opening 23 corresponding to the second display section of the liquid crystal panel 11, and has a recessed step 24 corresponding to the outer shape of the liquid crystal panel 11 around the opening 23 on the upper surface side. The printed wiring boards 14a are formed on the four sides of the lower surface.

Recesses 25 corresponding to 14b, 14c, and 14d are formed, and a recess 26 for storing the control lCl6 is formed above the recess 25 corresponding to one printed wiring board +4d. Also, the lower second
The support body 22 is provided with an opening 27 corresponding to the opening 23 of the first support body 22, and has the printed wiring board 14a on three sides around the opening 27 on the upper surface side.

Recesses 28 corresponding to 14b and 14C are formed, and in each recess 28, the driving I Cl2X and 12Y are formed.
A storage recess 29 is formed, and further, recesses 30 for wiring are formed at both ends of each recess 28.

Then, as described above, each tape carrier +3X, 13Y is connected to the liquid crystal panel 11, and the printed wiring board 1 is connected to each tape carrier +3X, 13Y.
After connecting the tape carriers 13X, 13Y to the liquid crystal panel 11, the first support 21 is placed on the back surface of the liquid crystal panel 11, and the tape carriers 13X, 13Y are connected to the liquid crystal panel 11 from the outside of the connection part with the liquid crystal panel 11. Fold it to the side almost in a U shape 1
111 Gero. In this case, if the polyimide base film corresponding to the bent part is partially removed, stress will not be generated in the OL B part even when it is bent.

Then, by bending each tape carrier 13X, 13Y, the three printed wiring boards 14a, 14b, 14c arranged on the back side of the liquid crystal panel 11 fit into the four parts 25 of the first support body 21, and further, IC1 for controlling the other 11 printed wiring boards +4d
6 is positioned in the storage recess 26 and fitted into the recess 25. And each printed wiring board 14a, 14b,
14c.

Connect +4d by soldering using the specified cable.

Next, the second support 22 is brought into contact with the lower surface of the first support 21, and each printed wiring board 14a is placed in the recess 28 of the second support 22.

14b and 14c and drive IC12X.
, +2Y are located in the storage recess 29, further supporting the printed wiring board 14d on a flat surface, and each printed wiring board 14a, 14b, 14c, 14d.
Connecting cables etc. 4 between the two are stored in the recess 30, thereby connecting each printed wiring board 1.
4a, 14b, 14c, and 14d are held between the first support 21 and the second support 22.

In addition, printed wiring boards 14a, 14b, 14c
.

The process of assembling the +4d and the pair of supports 21 and 22 is carried out using positioning pins previously provided on these and positioning holes that fit into the positioning pins.

As above, each tape carrier 12X, +2Y
The printed wiring board 14 having the circuit wiring input to the small printed wiring boards 14a, 14b, 14c,
By dividing and forming the printed wiring board 14d, it is possible to reduce the cost of the printed wiring board 14 compared to one made of a large single board, and therefore the cost of the liquid crystal display device can be reduced. The larger the area of the display section of the liquid crystal panel 11 (the larger the effect), the greater the effect.

Moreover, the printed wiring board 14 is a small printed wiring board 14.
Before dividing into a, 14b, 14c, and 14d and assembling them on the 1Y side of the liquid crystal panel 11,
Input terminals of tape carriers 13X and +3Y and printed wiring board 14a.

5 Solder the connections with the terminals 14b and 14c,
Moreover, this soldering is the connection to the polarizing plate 1 of the liquid crystal panel 11.
8, the polarizing plate 18 is not contaminated with flux, solder, etc., and the yield can be improved. Also, each printed wiring board 14a, 1
4b, 14c, 14d are a pair of supports 21.2
2, it can be easily and reliably placed in a predetermined position, and has good assemblability. In this case, as described above, each printed wiring board 14a, 14b.

If 14c, 14d and the pair of supports 21, 22 are connected and fixed using positioning pins, positioning holes, etc., assembly can be achieved without the need for special jigs and tools.

Note that, as in the above embodiment, each tape carrier 13X
, 13Y and place the connected printed wiring boards 14g, 14b, 14c on the back side of the liquid crystal panel 11, the width of the frame around the liquid crystal panel 11 can be reduced. In some cases, only part of the printed wiring boards 14a, 14b, and 14c, for example, the rear 13Y of the printed wiring board +4b, is bent, and the other printed wiring boards are placed outward in the same way as the printed wiring board +4d. Then, it may be held between a pair of supports 2] and 22.

〔Effect of the invention〕

According to the present invention, by dividing and forming a printed wiring board having circuit wiring input to each tape carrier into small printed wiring boards, the cost of printed wiring boards can be reduced compared to one made of a large single board. Therefore, the cost of the liquid crystal display device can be reduced. The cost reduction becomes more efficient as the area of the display section of the liquid crystal panel becomes larger.

In addition, the printed wiring board can be divided into small printed wiring boards, and the tape carrier and the terminals of the printed wiring board can be connected by soldering before being assembled on the back side of the liquid crystal panel. Since the connection can be made at a location away from the polarizing plate of the liquid crystal panel, the polarizing plate is not contaminated with flux, solder, etc., and the yield can be improved. By holding it between supports, it can be easily and reliably placed in a predetermined position, and has good assemblability.

[Brief explanation of drawings]

Fig. 3 is an exploded perspective view showing an embodiment of the liquid crystal display device according to the present invention, Fig. 2 is a plan view showing the assembled state of Fig. 1, Fig. 3 is a sectional view taken along line m-m in Fig. 2, Figure 4 is Figure 2 IV-
5 is an exploded perspective view showing a conventional liquid crystal display device, FIG. 6 is a plan view showing the assembled state of FIG. 5, and FIG. 7 is a sectional view of the section ■-■ in the figure It is. 11...Liquid crystal panel, +2X, +2Y...Drive IC, 13X, +3Y --Tape carrier,
14. 14g. 14b, 14c, 14d...Printed wiring board, 21.22...Support.

Claims (1)

[Claims] (1) A transmissive liquid crystal panel, a plurality of tape carriers each equipped with a driving IC that is connected at one end to a terminal on the periphery of the liquid crystal panel and drives the liquid crystal panel, and the other end of each tape carrier. a printed wiring board having circuit wiring connected to and input to each tape carrier; and a liquid crystal display device comprising: a printed wiring board that is divided into at least two parts, and a tape carrier on at least one side of the liquid crystal panel. The printed wiring board, which is bent at the outside of the connection part with the liquid crystal panel and connected to the tape carrier, is arranged on the back side of the liquid crystal panel, and the printed wiring board is arranged on the back side of the liquid crystal panel. A liquid crystal display device, characterized in that it is held between a pair of supports.